Paraffin Crystal and Deposition Control By Emulsification

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis laboratory investigation considers the effects of emulsions (via adding surfactants) and the formation and deposition of paraffin wax. This study relates the properties of added surfactant and emulsion characteristics with their wax deposition tendency. Parameters considered include the surfactant HLB (Hydrophilic Lipophilic Balance), molecular weight, and surfactant concentration. Two different series of commercial nonionic surfactants are included in this study; Triton-X (ethoxylated phenols) and Tween (sorbitan) products. The hydrocarbon phase is a model oil; a mixture of paraffin's with carbon numbers from C 21 to C 48 dissolved in n-decane (C 10 ). Emulsion characterization was done by IFT (interfacial tension), viscosity measurement, and optical microscopy.The wax deposition measurements were performed in a novel cell apparatus where stirring controls the hydrodynamics and mixing energy.The study results indicate adding surfactants to promote emulsification can reduce the tendency for wax deposition. Properties that induce tighter emulsions such as lower interfacial tension and greater shear rate lead to reduced paraffin deposition. Furthermore, the wax that does deposit from an emulsion is softer (lower average molecular weight) versus wax that deposits in the absence of any chemical. In contrast, the wax that deposits in the presence of some commercial polymer-based wax inhibitors can be even harder (higher average molecular weight) than the deposit formed in the absence of any chemical additive.

Rheological properties and flow behaviour of wax-stabilized water-in-oil emulsions

“…In general, an increase in crude oil shear or flow rate will decrease the rate of deposition (Singh, Venkatesan et al 2000;Hoteit, Banki et al 2008). Ahn et al, (Ahn, Wang et al 2005) suggested that the presence of emulsifiers may be able to selectively inhibit the deposition of higher molecular weight paraffin components (Ahn, Wang et al 2005). Visintin et al (Visintin, Lapasin et al 2005) concluded that crude oil flowing in the pipeline below its WAT temperature will not necessarily block the pipeline, given the fact that the fluid is always in movement (Venkatesan, Singh et al 2002;Visintin, Lapasin et al 2005).…”

Wax Deposition and Fouling

“…Dynamic wax deposition describes the formation of gel and the amount of wax deposited on pipeline walls, taking into account effects such as shear and flow rate (Ahn et al, 2005). Dynamic wax deposition describes the formation of gel and the amount of wax deposited on pipeline walls, taking into account effects such as shear and flow rate (Ahn et al, 2005).…”

Evaluation of Wax Deposition and Its Control During Production of Alaska North Slope Oils

“…into account the effect of shear rate, flow rate, water cut, etc. This simulation requires a knowledge of wax precipitation, and is obtained by thermodynamic modeling as discussed earlier (Ahn et al, 2005).…”